Supporters of the Nigerian president, Goodluck Jonathan, at a rally in Yenagoa, Nigeria.
Photograph: Tife Owolabi/EPA

Nigeria’s electoral commission will postpone next Saturday’s presidential and legislative elections for six weeks to give a new multinational force time to secure north-eastern areas under the sway of Boko Haram, an official close to the commission told the Associated Press on Saturday.

Millions could be disenfranchised if the voting went ahead while the Islamic extremists hold a large swath of the north-east and commit mayhem that has driven 1.5 million people from their homes.

Civil rights groups opposed to any postponement started a small protest on Saturday. Police prevented them from entering the electoral commission headquarters in Abuja, Nigeria’s capital. Armed police began deploying to block roads leading to the building.

The Nigerian official, who is knowledgeable of the discussions, said the Independent National Electoral Commission would announce the postponement later on Saturday. He spoke on condition of anonymity because of the sensitivity of the issue.

A major offensive with warplanes and ground troops from Chad and Nigeria already has forced the insurgents from a dozen towns and villages in the past 10 days. Even greater military strikes by more countries are planned.

African Union officials were ending a three-day meeting Saturday in Yaounde, Cameroon’s capital, to finalise details of a 7,500-strong force from Nigeria and its neighbours Chad, Cameroon, Benin and Niger. Details of funding, with the Africans wanting the United Nations and European Union to pay, may delay the mission.

Nigeria’s home-grown extremist group has responded with attacks on one town in Cameroon and two in Niger this week. Officials said more than 100 civilians were killed and 500 wounded in Cameroon. Niger said about 100 insurgents and one civilian died in attacks on Friday. Several security forces from both countries were killed.

International concern has increased along with the death toll; some 10,000 have been killed in the uprising in the past year compared with 2,000 in the four previous years, according to the US Council on Foreign Relations.

The United States has been urging Nigeria to press ahead with the voting. The US secretary of state, John Kerry, visited Nigeria two weeks ago and said that “one of the best ways to fight back against Boko Haram” was by holding credible and peaceful elections, on time.

“It’s imperative that these elections happen on time as scheduled,” Kerry said.

Officials in President Goodluck Jonathan’s administration have been calling for a postponement.

Any delay is opposed by an opposition coalition fielding former military dictator Muhammadu Buhari, though the opposition stands to take most votes in the north-east.

Supporters of both sides are threatening violence if their candidate does not win. Some 800 people were killed in riots in the mainly Muslim north after Buhari, a Muslim, lost 2011 elections to Jonathan, a Christian from the south.

A postponement will give electoral officials more time to deliver some 30 million voter cards. The commission had said the non-delivery of cards to nearly half of the 68.8 million registered voters was not a good reason to delay the vote.